Two guys tried trading josh jacobs for rehmondre Stevenson in a paid league

Im the commissioner for a league with like a $50 buy in. Two player in the league tried trading josh jacobs for rehmondre Stevenson straight up because one lost a bet to another one.

I vetoed it and said it wasn't fair to the the rest of the league to be doing that.

Now they are both saying im in the wrong and making a big deal out of it.

Is that something I should have just let happen?

Thx